The invention relates generally to gas turbine engines and, more particularly, to a manifold system for collecting air from one location of a gas turbine engine for use at another location.
In the gas turbine engine, and particularly in the aircraft engine, art it is known to extract air from the compressor section of the engine for use elsewhere in the engine or the aircraft, for example for providing high pressure air to the aircraft wing anti-icing system.
Various structures have been employed in the prior art to collect air from compressor stages. Typically, air is obtained from certain compressor stages and supplied to a manifold comprising a system of pipe segments surrounding the compressor casing. The manifold system is attached to the exterior of the gas turbine at the axial location of the compressor stage from which compressor air is to be extracted.
One significant limitation of the prior art manifold system construction is that the structure mounting the manifold to the compressor casing is subjected to substantial vibration cycles and temperature gradients during various parts of the flight cycle, resulting in build up of substantial stresses in the mount structures fastening the manifold apparatus to the compressor casing. These stresses can result in fatigue cracking in the mount structures and the manifold system itself, requiring early removal and replacement of manifold hardware at substantial cost in hardware and lost availability of the aircraft to the operator.
Accordingly, the present invention includes an air collecting manifold apparatus for a gas turbine engine having a supply tube surrounding a compressor casing configured as a plurality of generally circumferentially extending arcuate pipe segments disposed around the a compressor casing and connected to a system for distributing the air, for example to the aircraft wing anti-icing apparatus. The supply tube receives air from a system of feed tubes incorporating a plurality of flexible joints which allow for differential thermal growth and limit transmission of vibration from one component of the manifold structure to another.